update. bought one of these (see below link) off ebay but didn't make any diference in fact I think it made the hum louder...?
PRO DJ GOLD RCA PHONO GROUND LOOP ISOLATOR TO PREVENT UNWANTED HUM OR NOISE | eBay
PRO DJ GOLD RCA PHONO GROUND LOOP ISOLATOR TO PREVENT UNWANTED HUM OR NOISE | eBay
Hi all.
Still struggling with a hum on my LesBox. Has been fine for over a year but then something suddenly started buzzing. Checked leads, TT etc. Have replaced all of the mods components bar C15 and C16 which are next.
Have also been corresponding with Hi_Q but thought I'd run this past the open forum and give him some peace and quiet!
"Before I take it apart again, I've done the shorting test. 470ohm resistor across the test lead in each input. On powering up, output voltage on each channel gradually climbs and peaks at around 55vdc at about 10 seconds and then takes around 30 seconds to return back to 0vdc. Certainly not a pulse! What would that suggest?"
Any help is appreciated.
Still struggling with a hum on my LesBox. Has been fine for over a year but then something suddenly started buzzing. Checked leads, TT etc. Have replaced all of the mods components bar C15 and C16 which are next.
Have also been corresponding with Hi_Q but thought I'd run this past the open forum and give him some peace and quiet!
"Before I take it apart again, I've done the shorting test. 470ohm resistor across the test lead in each input. On powering up, output voltage on each channel gradually climbs and peaks at around 55vdc at about 10 seconds and then takes around 30 seconds to return back to 0vdc. Certainly not a pulse! What would that suggest?"
Any help is appreciated.
Sorry to read you are still having problems. The initial DC on the output is normal, the output capacitors temporarily pass a High Voltage pulse when V3 warms up, on to the output jacks. Normally with an amp applied to the outputs this pulse lasts just a few hundred milli-seconds, without an amp connected there is only the internal 1M resistor to discharge this and will take C x R seconds. With a 3.3uF capacitor and a 1M resistor this voltage should only be present for 3.3 seconds. As the fault suddenly appeared, was it due perhaps to a change you made in the system? Is there a GROUND missing somewhere or perhaps one that has appeared on the cartridge output lines? If the hum is present on both channels and definitely coming from the MS23 LesBox then perhaps the power supplies have gone wrong somewhere. Pull out one of the valves and check for correct regulated heater supplies of around 12.6V across pins 4 and 5 (counting anti-clockwise from the gap if looking down into the valve holder. If correct then maybe the HT supply is not as smooth as it should be due to perhaps partial failure in the encapsulated bridge rectifier. This latter problem was more common with the small round bridge rectifiers but not so common with the larger block rectifiers that Yaqin fitted later but still worth a check. Can you find out if the hum is indeed power line frequency 50 or 60 Hz or double that i.e. 100 or 120Hz? If it is power line then a poor or inappropriate Ground should be suspected but a power line frequency x 2 could indicate a fault with the HT system. A shame you are so far away, wish I could jump in a car and come over 
Les
LesI made a phono preamp 20 odd years ago with a single transistor front end and 353 op amp *RIAA* compliant curve.
the note here is that I tuned the preamp to make the ortofon MM cartridge have the same precieved frequency response as a CD. the Test record was Brothers in Arms Dire straights
It is still the best sounding pre I have heard. I am going to try 2 x 12ax7 to replace the LF353. I suspect Hi-Q has made it sound much more alive by changing the RIAA curve somewhat.
the note here is that I tuned the preamp to make the ortofon MM cartridge have the same precieved frequency response as a CD. the Test record was Brothers in Arms Dire straights
It is still the best sounding pre I have heard. I am going to try 2 x 12ax7 to replace the LF353. I suspect Hi-Q has made it sound much more alive by changing the RIAA curve somewhat.
New LesBox conversion convert!
Hi there DIY'ers.
Having recently had my MS-23B die on me (I now suspect poor soldering), I was faced with a conundrum:-
#1 Buy another MS-23B - I'd liked it so far and had no high-end comparison.
#2 Buy an alternative (ummm, what though?)
#3 LesBox conversion after testing the transformer in my MS-23B.
I ultimately opted for options 1 and 3, leaving me in a position to perform a proper side-by-side test later - the only way to really be sure how much of a difference it made. Truth be told, I opted for #1 because I was a little worried that despite being reasonably adept with a soldering iron I would mess up the conversion - that turned out to be no concern at all and I can attest to it having been both relatively simple and VERY worthwhile.
Now I think it's fair to say that there's a lot of twaddle written about incremental and potentially nonexistent gains in HiFi bits and pieces, so I'm a bit worried this is going to sound like the usual 'a veil was lifted' stuff I roll my eyes about. Bear with me though because this is not a minor improvement - it's really significant. I get to hear a lot of live music, given my location in Austin TX, so I'd like to think I have a decent reference for what my sound system should be replicating.
Here's my 'kit' :-
I have a Project Debut Carbon, which I've modified for $0 with a Stanley knife so it doesn't hum (I'll post that sometime now I'm registered here - the design intent of the motor suspension is pretty clear but execution leaves a bit to be desired), with an MP110 cartridge, feeding my MS23B and then on to a Yaqin MC10T with EH34's and 6N1P's from Voshkod in them. That goes out to some HTD3 Speakers which I've also modified so they're a bit more even-handed at the bottom end. They have passable ribbon drivers, so are quite detailed when fed with decent source material and after an extended break-in are very nice cabinets. I'd compare them to TDL's of old like the studio series, now I've lined the transmission lines.
What's the difference between the MS-23B and a LesBox modified one? :-
Playing 'Bop 'till you drop' by Ry Cooder is one of my fave ways to try out a system, so I'm very familiar with it. On several tracks, I was surprised to find things like cymbals popping out much more cleanly, with a very clear sense of what they're made of, if that makes sense. There's also a far more controlled low-end, with a somehow less ponderous feeling to it. I suppose a HiFi mag would describe it as 'tight and punchy', but I'll go for 'realistic'. Sibilance is much reduced too, which I'd always assumed was related to the cartridge more than anything else, but now stand corrected. There's a part in 'The very thing that makes you rich' which is really funky, where the music breaks down and Ry's guitar is barely perceptible in the distance, then surges forwards to take the song back. That's so much fun with the LesBox conversion that I think my wife might kill me soon. Swapping back to the MS-23B is dismal by comparison and takes all of the life out of the music. It's only now, typing that line, I realise why the comprehensive instructions Les wrote say 'putting life into the Yaqin MS-23B' - that is PRECISELY what's happening. I didn't even know how dull-sounding the MS-23B was until I 'raced' it against the LesBox one.
On to more modern vinyl, I played Lorde's 'Pure Heroine', which is very revealing of capabilities in the lower registers. The LesBox sounds controlled - relaxed but accurate. Individual notes are more cleanly presented and just more musical. Swapping back to the original was short-lived, because it sounded 'busy' and overall less like a live performance. I put the LesBox back in, just to be sure I wasn't breathing my own exhaust, and there it was again - music.
To make things as fair as possible, I put the original Shuguang 12AX7's into the LesBox version, which were pretty new and therefore comparable to the ones in the new unit. In the 3rd tube/valve position I put in an old Mullard ECC83 (UK manufacture). I also tried one of the Shuguangs (I do not recommend this) and even, at one point, a Raytheon 12AT7 (I don't recommend this either, but it was interesting to see how the lower internal resistance changed so much more than the overall gain).
In short, if you're even halfway to considering doing this, do it! The instructions are a bit daunting when you print them out, because Les has been very detailed so the pile of pages is thick, but it's really quite easy. Order up the parts, warm up the soldering iron and have at it - one you're finished you'll be wondering why you hadn't done it before.
I bottom-mounted my valve base and installed the capacitors near the front edge after putting the board back in (gave me room to hold the valve base retaining nuts with needle-nosed pliers), but I think Les' approach is probably better really, in that it allows for the tube shield to be installed. The wife likes the tubes showing however, and I know which side my bread's buttered...
Hi there DIY'ers.
Having recently had my MS-23B die on me (I now suspect poor soldering), I was faced with a conundrum:-
#1 Buy another MS-23B - I'd liked it so far and had no high-end comparison.
#2 Buy an alternative (ummm, what though?)
#3 LesBox conversion after testing the transformer in my MS-23B.
I ultimately opted for options 1 and 3, leaving me in a position to perform a proper side-by-side test later - the only way to really be sure how much of a difference it made. Truth be told, I opted for #1 because I was a little worried that despite being reasonably adept with a soldering iron I would mess up the conversion - that turned out to be no concern at all and I can attest to it having been both relatively simple and VERY worthwhile.
Now I think it's fair to say that there's a lot of twaddle written about incremental and potentially nonexistent gains in HiFi bits and pieces, so I'm a bit worried this is going to sound like the usual 'a veil was lifted' stuff I roll my eyes about. Bear with me though because this is not a minor improvement - it's really significant. I get to hear a lot of live music, given my location in Austin TX, so I'd like to think I have a decent reference for what my sound system should be replicating.
Here's my 'kit' :-
I have a Project Debut Carbon, which I've modified for $0 with a Stanley knife so it doesn't hum (I'll post that sometime now I'm registered here - the design intent of the motor suspension is pretty clear but execution leaves a bit to be desired), with an MP110 cartridge, feeding my MS23B and then on to a Yaqin MC10T with EH34's and 6N1P's from Voshkod in them. That goes out to some HTD3 Speakers which I've also modified so they're a bit more even-handed at the bottom end. They have passable ribbon drivers, so are quite detailed when fed with decent source material and after an extended break-in are very nice cabinets. I'd compare them to TDL's of old like the studio series, now I've lined the transmission lines.
What's the difference between the MS-23B and a LesBox modified one? :-
Playing 'Bop 'till you drop' by Ry Cooder is one of my fave ways to try out a system, so I'm very familiar with it. On several tracks, I was surprised to find things like cymbals popping out much more cleanly, with a very clear sense of what they're made of, if that makes sense. There's also a far more controlled low-end, with a somehow less ponderous feeling to it. I suppose a HiFi mag would describe it as 'tight and punchy', but I'll go for 'realistic'. Sibilance is much reduced too, which I'd always assumed was related to the cartridge more than anything else, but now stand corrected. There's a part in 'The very thing that makes you rich' which is really funky, where the music breaks down and Ry's guitar is barely perceptible in the distance, then surges forwards to take the song back. That's so much fun with the LesBox conversion that I think my wife might kill me soon. Swapping back to the MS-23B is dismal by comparison and takes all of the life out of the music. It's only now, typing that line, I realise why the comprehensive instructions Les wrote say 'putting life into the Yaqin MS-23B' - that is PRECISELY what's happening. I didn't even know how dull-sounding the MS-23B was until I 'raced' it against the LesBox one.
On to more modern vinyl, I played Lorde's 'Pure Heroine', which is very revealing of capabilities in the lower registers. The LesBox sounds controlled - relaxed but accurate. Individual notes are more cleanly presented and just more musical. Swapping back to the original was short-lived, because it sounded 'busy' and overall less like a live performance. I put the LesBox back in, just to be sure I wasn't breathing my own exhaust, and there it was again - music.
To make things as fair as possible, I put the original Shuguang 12AX7's into the LesBox version, which were pretty new and therefore comparable to the ones in the new unit. In the 3rd tube/valve position I put in an old Mullard ECC83 (UK manufacture). I also tried one of the Shuguangs (I do not recommend this) and even, at one point, a Raytheon 12AT7 (I don't recommend this either, but it was interesting to see how the lower internal resistance changed so much more than the overall gain).
In short, if you're even halfway to considering doing this, do it! The instructions are a bit daunting when you print them out, because Les has been very detailed so the pile of pages is thick, but it's really quite easy. Order up the parts, warm up the soldering iron and have at it - one you're finished you'll be wondering why you hadn't done it before.
I bottom-mounted my valve base and installed the capacitors near the front edge after putting the board back in (gave me room to hold the valve base retaining nuts with needle-nosed pliers), but I think Les' approach is probably better really, in that it allows for the tube shield to be installed. The wife likes the tubes showing however, and I know which side my bread's buttered...
Thanks Ed for your write up of the LesBox converted MS23. I seem to have missed some earlier posts which I apologize for as I genuinely missed them. The 75k//18k combination provide the correct EQ time constant so please keep to them unless you can find a 14,516 Ohm resistor
My original IP decided to shut down their service so I had to change it, I convinced myself that all the Forums I am on had been notified, again I apologize.
The new location is:-
https://goo.gl/YxMgRN
If you have not yet seen it, a good video of the conversion process can be seen here on YouTube:-
https://youtu.be/eSt5KbBcDEo
BTW All the very best to everyone for a Happy Christmas and a fabulous 2017.
My original IP decided to shut down their service so I had to change it, I convinced myself that all the Forums I am on had been notified, again I apologize.
The new location is:-
https://goo.gl/YxMgRN
If you have not yet seen it, a good video of the conversion process can be seen here on YouTube:-
https://youtu.be/eSt5KbBcDEo
BTW All the very best to everyone for a Happy Christmas and a fabulous 2017.
No! stocktrader200 - the conversion attempts to keep strictly to the RIAA despite the constraints of the MS22/23 PCB and inherent stray capacitance etc.
If you wire out these strays in a new environment, the RIAA gets even better especially with more direct point to point wiring. I achieve this in my LesBox Mk.3 layout using a standard Hammond die-cast box which many say sounds even better. see http://goo.gl/zRYoCI
With regard to doing conversions for others, I have had to reluctantly decline any from outside the UK due to postage costs which can be as much as $200 both ways. Also I am getting charged $80 by UK Customs even though the units are being returned within 7 days! So far I have been able to absorb these costs, totaling well over $3000, but now I am retired I have to survive purely on a State Pension. :-(
I may be able to help though with any parts you are having trouble to locate.
Les
Les,
I just read through all posts and I must say hearty thank you! I was impressed with your helpful posts and you've addressed all the questions on this thread. Just as I was about to say my thanks to that, your last post threw me overboard! Wow. As if your intellectual contribution wasn't enough.., Please keep posting and contributing to the brain bank, but do not go out of your way to absorb costs for others.
I just read through all posts and I must say hearty thank you! I was impressed with your helpful posts and you've addressed all the questions on this thread. Just as I was about to say my thanks to that, your last post threw me overboard! Wow. As if your intellectual contribution wasn't enough.., Please keep posting and contributing to the brain bank, but do not go out of your way to absorb costs for others.
Hey Les (or anyone else who feels qualified to answer),
I just got my MS23b, and to be honest I think this unit is fantastic right out of the box (at least after swapping the stock tubes for a matched pair of Sovtek 12AX7LPS's). But there is nothing I enjoy more than a good "tinker", so I am about to undertake the conversion!
My question is regarding the 8200pF 1% Silver Mica Caps. As was discussed earlier in the thread, this part is very hard to source. They are still available at Mouser Electronics, but they want $32 +shipping for the pair. OUCH! However I already have some in 5%, so would it be alright to use them? Or is the tolerance critical here?
John
OK, so I found the answer to this question right there in the PDF on page 3 under "suggestions":
Boy do I feel like a fool, I probably skimmed over this a half dozen times...
I just got my MS23b, and to be honest I think this unit is fantastic right out of the box (at least after swapping the stock tubes for a matched pair of Sovtek 12AX7LPS's). But there is nothing I enjoy more than a good "tinker", so I am about to undertake the conversion!
My question is regarding the 8200pF 1% Silver Mica Caps. As was discussed earlier in the thread, this part is very hard to source. They are still available at Mouser Electronics, but they want $32 +shipping for the pair. OUCH! However I already have some in 5%, so would it be alright to use them? Or is the tolerance critical here?
John
OK, so I found the answer to this question right there in the PDF on page 3 under "suggestions":
Boy do I feel like a fool, I probably skimmed over this a half dozen times...
OK Celebabe, if you get stuck I may be able to find a pair in my rapidly depleting stores. These are 1% as advertised here:-
Lemco 8200pF 1% silver mica capacitors | eBay
Regards, Les
Lemco 8200pF 1% silver mica capacitors | eBay
Regards, Les
Thanks for the reply Les. As I said, I already have a pair with 5% tolerance, and since you say you tested with the same and found them satisfactory I think I will go with them.
BTW - I've noticed that a lot of people go without the screening cans (whether LesBox converted or not). For anyone planning on doing the conversion and not using them, at least on the 3rd tube, I think I have an idea of how to mount the socket that will make reassembly and future circuit board removal much simpler. And you will even be able to use the top side shield without modification! In fact if you leave the cans on the 2 channel tubes, the unit will look stock at first glance. Personally I plan on not using the cans and raising those 2 tubes with socket savers, just for looks...
I will post pictures when I complete the work.
BTW - I've noticed that a lot of people go without the screening cans (whether LesBox converted or not). For anyone planning on doing the conversion and not using them, at least on the 3rd tube, I think I have an idea of how to mount the socket that will make reassembly and future circuit board removal much simpler. And you will even be able to use the top side shield without modification! In fact if you leave the cans on the 2 channel tubes, the unit will look stock at first glance. Personally I plan on not using the cans and raising those 2 tubes with socket savers, just for looks...
I will post pictures when I complete the work.
Here it is:
And the best part is that the whole thing just slides in and out of the chassis.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
And the best part is that the whole thing just slides in and out of the chassis.
Last edited:
Celebabe that is super - can I append your photos to the conversion instructions? Orange included
By all means Les, please do! If you need higher resolution versions or more detailed shots just let me know by PM, I'd be more than happy.
John
Well, I finally got around to completing the conversion. (Huge snowstorm here, so an extra day off from work...) My earlier pictures were of a stripped board with no track cuts or new components other than C15 & C16 in place.
All I can say is WOW! It truly sounds AMAZING. Beautiful warm tones, great definition and a kick to the bass that was missing before. Too anyone considering this project, I say go for it. It is TOTALLY WORTH IT!
And to Les I just want to say, Thank-You So Much for sharing your work with the world.
John
All I can say is WOW! It truly sounds AMAZING. Beautiful warm tones, great definition and a kick to the bass that was missing before. Too anyone considering this project, I say go for it. It is TOTALLY WORTH IT!
And to Les I just want to say, Thank-You So Much for sharing your work with the world.
John